Carburation and fuel feed system



June 7, 1932. R. F. BRACKE CARBURATION AND FUEL FEED S YSTEM Filed Sept. 17, 1928 2 Sheets-Sheet l I 056, 11 F firacke,

e w *M @y June 7, 1932.

I R. F. BRACKE CARBURATION AND FUEL FEED SYSTEM Filed Sept. 17, 1928 2 Sheets-Sheet 2 Patented June 7, ,1932' UNITED STATES PATENT OFFICE.

noun 1'. amen, or cnroneo, Tumors, assrenon. 'ro CURTIS B. cm, TRUSTEE,

. or ennncon, ILLINOIS GABBURATION AND FUEL FEED SYSTEM My invention relates to carburation and fuel feed systems for internal combustion engines and particularly for motor vehicle engines, wherein engine suction is utilized to lift fuel from a low level main supply tank to the carburetor. Y

One of the objects of my invention is to provide an improved carburation and fuel feed system in which primary air for the carburetor is admitted to the system at the low level main supply tank where it receives a fuel charge and the mixture thus formed conducted to the induction passage of the carburetor.

16 Another object is to providea carburation and fuel feed system whereinan excess amount of fuel is lifted into the primary air stream at the main fuel tank which is conveyed by the air stream to the fuel chamher of the carburetor and is there deposited and utilized as a source of supply or the fuel nozzle of the carburetor.

A further object is to provide a carburation and fuel feed system which will operate 2 successfully when the vertical distance between the carburetor and main supply tank is relatively great.

Another object is to provide a carburation and fuel feed system wherein differences in the level of fuel in the main supply tank do not appreciably affect the fuel lifting characteristic of the system.

Another object is to provide a carburation .7 and fuel feed system wherein the depression at the main fuel nozzle is maintained higher than the depression at the discharge end of the primary air passage, thus assuring the delivery of fuel through the fuel nozzle.

Other objects and advantages will hereinafter appear.

My improved carburation and fuel feed system' is illustrated in the accompanying drawings, in which Fig. 1 is a sectional view of a motor vehicle illustrating the relative position of the several elements of the system. and

Fig. 2 is a sectional view of the mechanism comprising the system as illustrated in Fig.1.

In general, my improved carburation and 50 fuel feed system comprises a carburetor A tained at atmospheric pressure by means of having a fuel or float chamber B, a primary air passage C connecting the induction passage D of the carburetor through the fuel chamber to the interior of a main fuel supply tank E which is maintained at atmospheric pressure and suction multiplying means F at the tank end of the primary air passage for lifting fuel from the tank into the air passa e.

Ihe carburetor A has for its secondary inlet a relatively large passage 10 having a butterfly choke valve 11 therein which communicates with the induction passage D throu h a spring pressed secondary air valve 12. he air valve 12 functions to maintain a substantially constant depression in the induction passage D and is adjustable bymanipulation of a thumb screw 13 for varying the compression of the spring 14 which opposes the valve spring 15. The s ring 15 tends to maintain the valve 12 closed against its seat 16. A butterfly throttle valve 17 is disposed in the delivery port 18 of the induction passage for controlling the delivery'of the fuel mixture to the engine manifold 19.

The primary air passage C comprises a bore, a port or passage 25 interconnecting the induction passage D with the upper por tion' of the fuel chamber B and a tube 26 having one end communicating at 27 with the upper region of the fuel chamber and having its other end connected to the outlet 28 of a suction multiplying Venturi tube 29 mounted upon a plug 30 which extends I through the top wall of the main supply tank E. The inlet 31 of the Venturi tube communicates with a bore 3:2 in plug 30, the other end of which extends to the interior of tank E. The pressure in the tank E is maina vented filler cap 33.

The Venturi tube 29 has a plurality of radial passages 35 therethrough at its throat 36. all of which communicate with the fuel passage 37. having its opposite end connected to a vertical tube 38 which extends to the, lower region of the main supply tank.

It is thus apparent that the passage of primary air to the induction patwage D of the carburetor from the interior of fuel tank E will lift fuel to the throat 36 of the Venturi B. The fuel vapor passes on to the induction chamber D through bore 25 while the liquid fuel is deposited in the fuel chamber.

Means for shutting off the supply of excess fuel from the fuel or induction chamber B is provided in a float 40 mounted within float chamber B and having a valve or shutter plate 41 which is moved over the delivery end of tube 26 at 27 to diminish the volume of primary air drawn from the tank E. The closing of the shutter 41, as described, reduces the depression in the tube 26 and hence reduces the velocity of air as it passes through the throat 36 of Ventrui tube 29. This condition resultsin the passage of fuel vapor through tube 26 which is delivered to induction passage D through bore 25 together with sufiicient excess fuel to compensate for the fuel which is drawn through the fuel nozzle 45 from fuel chamber B.

The nozzle 45 is disposed with its outlet 46 at the restricted or throat portion 47 of a Venturi like constriction formed in the in duction passage D. Induction passage D is so formed to maintain the depression at the outlet 46 of a fuel nozzle greater than the depression at the delivery orifice of bore 25, thus assuring the delivery of fuel through nozzle 45.

A vertical perforated baflle plate 50 is mounted within fuel chamber B to prevent excessive movement of fuel in the chamber and hence erratic operation of the float.

In operation my improved carburation and fuel feed system functions to maintain the level of fuel in the float chamber B at the position indicated in Fig. 2 with the primary air passage sufiiciently restricted by the shutter 41 as to draw but a small quantity of excess fuel into the primary air stream, which is just sufficient to compensate for the fuel delivered to the induction passage D through fuel nozzle 45. 7

When, however. the level of the fuel in chamber B lowers materially, the depression in tube 26 increases because of the decrease in the restriction formed by shutter 41 that is, increase in the opening and a greater excess of fuel is lifted to Venturi 29 where it is carried along with the primary air stream and deposited into the fuel chamber. As the float 40 rises shutter 41 will again assume the position shown in Fig. 2- thus restoring the system to its normal condition.

The depression in fuel chamber B will at no time exceed the depression 'to which the outlet 46 of fuel nozzle 45 is subjected because of the Venturi action of the induction passage D at its restricted or throat portion 47. This structure assures the delivery of fuel from the chamber B under all normal operating conditions. The secondary air valve 12 functions to maintain the induction passage D at a substantially uniformdepression thereby insuring the lift of fuel from the main supply tank E to the carburetor at all throttle positions.

lVhen the engine is shut off the fuel which is then in tube 26 is free to flow back through Venturi tube 29 where it may fall directly into the tank through bore 32.

The depression at throat 36 of Venturi 29 is suflicient to lift fuel many, times the depth of the ordinary type of main fuel supply tank and hence changes in the level in the fuel in the tank do not appreciably affect the delivery of fuel to the carburetor. Furthermore if insufficient fuel is delivered to the fuel chamber B, the float 40 will so operate shutter 41 as to cause the depression in tube 26 to increase and carry a greater quantity of fuel to the chamber.

\Vhat I claim is new and desire to secure by Letters Patent of the United States is:

1. In combination an induction chamber adapted for direct connection to the intake manifold of an internal combustion, engine, a main fuel supply tank, a primary air passage communicating with the induction chamber at one end and extending to the main fuel tank, a suction multiplying Venturi tube associated with the primary air passage at the fuel tank for lifting fuel from the tank into the passage, means for maintaining a predetermined depression in the induction chamber, a constant level fuel chamber and means therein for variably restricting the primary air passage outlet at said one end and a fuel nozzle communicating with the chamber for supplying additional fuel to the induction chamber and for supplying all of the fuel to the induction chamber at idle throttle position.

2. In combination an induction passage adapted for connection with the intake manifold of an internal combustion engine and having a restricted portion, a main fuel supply tank, a relatively large primary air passage communicating with the induction passage at one end and extending to the main fuel supply tank, a suction multiplying Venturi tube associated with the primary a1r passage at the fuel tank for lifting fuel from the tank into the passage, said passage at the Venturi tube having a fuel passage and a drain passage both serving to admit air, a constant level fuel chamber, means in said chamber for restricting the opening in the said one end of said primary air passage and a fuel nozzle in the restricted portion of the induction passage and communicating with the fuel chamber.

3. In combination with an induction passage adapted for connection with the intake manifold of an internal combustion engine and having a restricted throat portion, a fuel chamber adjacent said throat andhaving a passage communicating with the induction chamber above the restricted throat, alow level main fuel tank, a primary air passage communicating at one end with the fuel chamber and at the other end with the fuel tank and havin a restricted portion adjacent the tank with passages leading thereto through which the fuel 1s drawn, a vented 1o cap for the tank, means within the fuel chamber and controllin the outlet end of the primary air passage or maintaining a uniform level of fuel in the fuel chamber and regulating the restriction of the outlet end of the primary air passage, a nozzle in the throat of the induction passage and fed from the fuel chamber, and a valve for maintaining A a relatively constant depression in the induction passage. In witness whereof, I hereunto subscribe my name this 14th day of Sept., 1928.

ROBERT F. BRAGKE. 

